#include <stdio.h>

int main(int argc, char const *argv[])
{
    int x;
    int ret = 0;

    scanf("%d", &x);
    int t = x;

    while (t > 1)
    {
        t /= 2;
        ret++;
    }

    printf("log2 of %d is %d\n", x, ret);
    
    return 0;
}